For example, starches have been used as natural binders in the production of paper coatings to bind pigment particles together to form a smooth coating substrate on the paper surface. Starches are used in paper coatings primarily for their economy and ease of use, but are inferior to other binders such as proteins and synthetic latex in their binding ability and coating surface properties such as print gloss. Starch dextrins have also been used in the production of paper adhesives for purposes of remoistening sealants, for box carton gluing, and other purposes. The starch dextrins suffer from relatively low dry binding strength compared to other adhesives and do not provide significant water repellency to the dry adhesive.
Proteins have also been used as natural binders in paper coatings and have demonstrated better binding ability than starches, but are difficult to use and need to be chemically modified and/or depolymerized before use in order to obtain reasonable coating viscosity levels. Protein based adhesives, binders and coatings also tend to be more expensive than starch based adhesives, binders and coatings. Additionally, proteins have been used as a replacement for resins such as urea/formaldehyde resins for gluing wood layers in the production of plywood. The urea/formaldehyde adhesive provides good binding ability to the wood layers, as well as provides good water repellency to the adhesive. Proteins, in combination with a water proofing resin, have been used to replace the urea/formaldehyde adhesive in plywood manufacture. Adhesive formulations using an unmodified protein, however, suffer from high viscosity and low solids content compared to the urea/formaldehyde formulation, thus impacting drying times and overall production.
Thus, there exists a need for an adhesive, binder or coating that has ease of use, good binding abilities and optimized cost.